Operations, such as surveying, drilling, wireline testing, completions, production, planning and field analysis, are typically performed to locate and gather valuable downhole fluids. Surveys are often performed using acquisition methodologies, such as seismic scanners or surveyors to generate maps of underground formations. These formations are often analyzed to determine the presence of subterranean assets, such as valuable fluids or minerals, or to determine if the formations have characteristics suitable for storing fluids. The subterranean assets are not limited to hydrocarbon such as oil, throughout this document, the terms “oilfield” and “oilfield operation” may be used interchangeably with the terms “field” and “field operation” to refer to a field having any types of valuable fluids or minerals and field operations relating to any of such subterranean assets.
During the field operations, data is typically collected for analysis and/or monitoring of the operations. Such data may include, for instance, information regarding subterranean formations, equipment, and historical and/or other data. Data concerning the subterranean formation is collected using a variety of sources. Such formation data may be static or dynamic. Static data relates to, for instance, formation structure and geological stratigraphy that define geological structures of the subterranean formation. Dynamic data relates to, for instance, fluids flowing through the geologic structures of the subterranean formation over time. Such static and/or dynamic data may be collected to learn more about the formations and the valuable assets contained therein.
The data may be used to predict downhole conditions and make decisions concerning field operations. Such decisions may involve well planning, well targeting, well completions, operating levels, production rates and other operations and/or operating parameters. There are usually a large number of variables and large quantities of data to consider in analyzing field operations. It is, therefore, often useful to model the behavior of the field operation to determine the desired course of action. During the ongoing operations, the operating parameters may be adjusted as field conditions change and new information is received. Techniques have been developed to model the behavior of various aspects of field operations, such as geological structures, downhole reservoirs, wellbores, surface facilities, as well as other portions of the field operation.
Stratigraphy is fundamental to the discipline of geology in describing the spatial, geometrical, structural, sequential and temporal relationships of rock units. In response to the formation of rocks in highly variable depositional environments and with varying sedimentary compositions, stratigraphic approaches span a wide range of disciplines, such as, litho-, bio-, chrono-, magneto-, seismic-, sequence- and chemo-stratigraphy. Generally, in early stage geological exploration, little or no information is available on sediment characteristics. The identification and analysis of a potential hydrocarbon reservoir is a matter of interpretation and analysis of seismic reflection data.
Seismic surveying is generally performed by imparting energy to the earth at one or more source locations, for example, by way of controlled explosion, mechanical input etc. Return energy is then measured at surface receiver locations at varying distances and azimuths from the source location. The travel time of energy from source to receiver, via reflections and refractions from interfaces of subsurface strata, indicates the depth and orientation of such strata. Seismic data, as collected via the receiver, within a volume of interest is referred to as seismic volume. A seismic volume can be displayed as seismic images based on different sampling resolutions and viewing orientations as well as subject to various different seismic amplitude processing techniques to enhance or highlight seismic reflection patterns.
Seismic images indirectly show the distribution of material deposited over large areas. The spatial (and temporal) variability of stacking patterns, or sequences, observed in seismic images relates to depositional environments and post-depositional processes, such as erosion and tectonic activity. During seismic interpretation, reflection patterns in the seismic images linking depositional environments and vertical stacking order to sequence of deposition and, thus, relative timing, enables the geological history of the subsurface to be deciphered and leads to the estimation of probable sedimentary characteristics. In this manner, a potential hydrocarbon reservoir may be identified and analyzed based on interpretation and analysis of seismic reflection data. However, performing seismic data interpretation over large seismic volumes can be a daunting task, particularly if done manually.